In the early days of the development of vehicle occupant restraint systems using airbags, the main focus was initially to recognize a restraint situation reliably and quickly as well as to cause the airbag to be filled rapidly in order to protect a vehicle occupant. Starting from those basic requirements, the demands made of modern vehicle occupant restraint systems have increased dramatically since that time. Additional requirements that have come to the fore are, for example, that the response of the restraint system be adapted to the restraint position of the vehicle occupant and to the anticipated impact momentum of the vehicle occupant.
The state of the art describes numerous attempts to meet these ever-higher demands. Thus, for example, U.S. patent application 2004/0012180 A1 describes a vehicle occupant restraint system that can release an additional airbag volume as a function of the situation and, at the same time, can close an opening in the module housing. The basic idea here is to be able to use an inexpensive, one-stage gas generator that is configured for the optimal filling of the maximum airbag volume. In order to achieve approximately the same airbag hardness for the smaller airbag volume, excess gas is vented through an opening in the module housing. Depending on the embodiment, the opening or the closing of airbag openings can be coupled to the release of the larger airbag volume.
The object of the present invention is to create an airbag module with simple means that responds as specifically as possible to changes in individual parameters of a restraint situation such as, for example, the vehicle occupant position or the anticipated impact momentum of the vehicle occupant.